dead-simple-counter-win-rs

A dead simple counter windows app written in Rust with windows-rs library for demonstration purpose. You can use this app as Your First Windows Application.

Develop

• Rust
• Win32 API
• NSIS
• GitHub Action

Files

main.rs

It's a good practice to have a struct to hold the states of your app instead of using global variables. So we define struct Counter which has two fields: counter and output_handle and initiate in main function with Box::leak to retrive the pointer of the Counter. We pass the pointer to CreateWindowExW as lpparam argument. Here is the brif code.

struct Counter {
    counter: i32,
    output_handle: HWND,
}

let lparam: *mut Counter = Box::leak(Box::new(Counter{
    counter: 1,
    output_handle: HWND(0),
}));

let hwnd = CreateWindowExW(
    // ... ...
    Some(lparam as *mut c_void),
);

We can only receive this pointer on VM_CREATE message once, so what we should do next is to store the value to GWLP_USERDATA which is allocated by windows. then we are able to access this pointer on every message reached.

// Pseudocode
fn window_proc(_, _, _, lparam: LPARAM) {
    if is WM_CREATE message {
        let cs = lparam.0 as *const CREATESTRUCTW;
        let counter = (*cs).lpCreateParams as *mut Counter;
        SetWindowLongPtrW(hwnd, GWLP_USERDATA, counter as _);
    },
}

To access the pointer we can use

let counter_ptr = GetWindowLongPtrW(parent, GWLP_USERDATA) as *mut Counter;
if let Some(c) = counter_ptr.as_mut() {
    c.counter += delta;
}

It's not easy for me to accomplish all this stuff, I have asked for help in StackOverflow, this is the post, and eventually I found the solution on GitHub robmikh/minesweeper-rs.

counter.sni

NSIS is a professional open source system to create Windows installers, it's widely used in open source projects.

Choose installation folder

Details of processing

Finished page

.github/workflows/release.yml

Thanks to GitHub Action we can effortlessly build our releases. It runs on Windows Server 2022 to build app with Rust and NSIS. The image GitHub provided has already installed most developing languages and runtimes including Rust and NSIS. Then run cargo build --release to build app from src/main.rs. After building the app all files are fulfilled, we can run makensis counter.sni to package app resources and setup instructions into CounterSetup.exe. Finally we upload the binary to GitHub release as an asset for users to download.